U.S. patent application number 16/740990 was filed with the patent office on 2020-05-14 for methods and systems for real-time, in-process measurement of coatings on metal substrates using optical systems.
The applicant listed for this patent is Sensory Analytics, LLC. Invention is credited to Greg Frisby, Vivek C. Komaragiri.
Application Number | 20200149876 16/740990 |
Document ID | / |
Family ID | 65002276 |
Filed Date | 2020-05-14 |
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United States Patent
Application |
20200149876 |
Kind Code |
A1 |
Komaragiri; Vivek C. ; et
al. |
May 14, 2020 |
METHODS AND SYSTEMS FOR REAL-TIME, IN-PROCESS MEASUREMENT OF
COATINGS ON METAL SUBSTRATES USING OPTICAL SYSTEMS
Abstract
A method for measuring the thickness of coatings on metal
substrates comprises illuminating a sample comprising a substrate
and a coating with light waves of varying wavelengths from a light
source, receiving the light waves reflected by the sample at a
light collector, diffracting the light waves into a plurality of
component wavelengths with a grating, detecting the light
intensities of the plurality of component wavelengths at a detector
array, generating a reflectance spectral curve using the detected
light intensities for each of the plurality of component
wavelengths, calculating the thickness of the coating from the
reflectance spectral curves of the component wavelengths.
Inventors: |
Komaragiri; Vivek C.;
(Greensboro, NC) ; Frisby; Greg; (Greensboro,
NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sensory Analytics, LLC |
Greensboro |
NC |
US |
|
|
Family ID: |
65002276 |
Appl. No.: |
16/740990 |
Filed: |
January 13, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US18/41541 |
Jul 11, 2018 |
|
|
|
16740990 |
|
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62531484 |
Jul 12, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01B 11/0625 20130101;
G01N 21/952 20130101; G01J 3/18 20130101; G01J 3/1804 20130101;
G01J 3/0208 20130101; G01N 2021/8427 20130101; G01N 2021/8918
20130101; G01N 21/8422 20130101; G01N 21/95 20130101 |
International
Class: |
G01B 11/06 20060101
G01B011/06 |
Claims
1. A method for measuring the thickness of coatings on metal
substrates comprising: illuminating a sample comprising a substrate
and a coating with light waves of varying wavelengths from a light
source; receiving the light waves reflected by the sample at a
light collector; diffracting the light waves into a plurality of
component wavelengths with a grating; detecting the light
intensities of the plurality of component wavelengths at a detector
array; generating a reflectance spectral curve using the detected
light intensities for each of the plurality of component
wavelengths; calculating the thickness of the coating from the
reflectance spectral curves of the component wavelengths.
2. The method of claim 1, wherein the sample is continuously
moving.
3. The method of claim 1, wherein the light waves of varying
wavelengths are between about 1000 nm and about 2500 nm.
4. The method of claim 1, wherein the light source is part of a
bifurcated fiber optic cable.
5. The method of claim 1, wherein the light collector is part of a
bifurcated fiber optic cable.
6. The method of claim 1, wherein the grating matches the spectral
response over a specific wavelength range suitable for the
sample.
7. The method of claim 1, wherein the frequency of the reflectance
spectral curve is directly proportional to the thickness of the
coating.
8. The method of claim 1, wherein calculating the thickness of the
coating occurs in real-time.
9. The method of claim 1 further comprising detecting changes in
the distance between the sample and the light source.
10. The method of claim 9, wherein illuminating the sample includes
varying the intensity of the light waves based on the distance
between the sample and the light source.
11. The method of claim 1, further comprising adjusting the amount
of coating applied to the substrate in real time based on the
calculated thickness of the coating.
12. A system for measuring the thickness of coatings on metal
substrates comprising: a processor; a light source in communication
with the processor, the light source configured to illuminate a
sample comprising a substrate and a coating with light waves of
varying wavelengths; a detection module in communication with the
processor comprising: a light collector configured to receive light
waves reflected by the sample; a grating configured to diffract the
light waves into a plurality of component wavelengths; a detector
array configured to detect the light intensities of each of the
plurality of component wavelengths; a memory in communication with
the processor, wherein the memory comprises computer program code
executable by the processor configured to: generate a reflectance
spectral curve using the detected light intensities for each of the
plurality of component wavelengths; calculate the thickness of the
coating from the reflectance spectral curves of the component
wavelengths; display the calculated thickness of the coating in
real-time.
13. The system of claim 12, wherein the sample is continuously
moving.
14. The system of claim 12, wherein the light waves of varying
wavelengths are between about 1000 nm and about 2500 nm.
15. The system of claim 12, wherein the light source is part of a
bifurcated fiber optic cable.
16. The system of claim 12, wherein the light collector is part of
a bifurcated fiber optic cable.
17. The system of claim 12, wherein the grating matches the
spectral response over a specific wavelength range suitable for the
sample.
18. The system of claim 12, wherein the frequency of the
reflectance spectral curve is directly proportional to the
thickness of the coating.
19. The system of claim 12, wherein calculating the thickness of
the coating occurs in real-time.
20. The system of claim 12, wherein the computer program code is
further configured to detect changes in the distance between the
sample and the light source.
21. The system of claim 20, wherein illuminating the sample
includes varying the intensity of the light waves based on the
distance between the sample and the light source.
22. The system of claim 12, further comprising a computer
controlling a coil coating applicator configured to receive the
calculated thickness of the coating and adjust the amount of
coating applied to the substrate in real-time.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS appples
[0001] This application is a continuation of International Patent
Application No. PCT/US18/41541 entitled "METHODS AND SYSTEMS FOR
REAL-TIME, IN-PROCESS MEASUREMENT OF COATINGS ON METAL SUBSTRATES
USING OPTICAL SYSTEMS" filed on Jul. 11, 2018, which claims
priority to and benefit of U.S. Provisional Patent Application No.
62/531,484 entitled "Methods and Systems for Real-Time, In-Process
Measurement of Coatings on Metal Substrates Using Optical Systems"
filed Jul. 12, 2017, the entire contents of which are all hereby
incorporated herein by reference.
BACKGROUND OF THE DISCLOSURE
[0002] The present disclosure generally relates to methods and
systems for measuring the thickness of clear and pigmented coatings
applied on various metal substrates, more specifically tailored to
the products in the coil coating industry. Embodiments include
methods and systems for real-time, in-process measurement of
applied primer and/or top coat coating thickness, and more
particularly methods and systems for real-time, in-process
measurement of coating thickness of a combination of one or more
layers on a static or a moving substrate.
[0003] In coil coating industry, most products are made by
application of one or two or more layers of pigmented coatings
applied on both sides of a metal coil. These coated products can be
used in a wide range of industries such as construction,
automobile, aerospace, appliances and so on. The coating is applied
on a metal substrate at a relatively high speed of about 500 to
1000 feet per minute. Several alternative techniques exist to
measure the thickness of the coating in an offline inspection, but
there are no non-contact or non-destructive, non-radioactive
methods for measuring paint thickness in real-time on the moving
metal substrate during the coating process. The current widely used
technique for measuring thickness, and thereby controlling quality,
is an offline destructive inspection method measuring the coating
thickness of approximately an area of 1 mm.sup.2 on a coil that has
an area of several thousand square meters. In this method, the
thickness of the coating on the remainder of the coil is simply
assumed to be similar or identical to the measured sample area. The
current methods are time-consuming and provide very little
meaningful data for quality and process control improvements. Other
alternate methods include slow and tedious paint weight
measurements based on stripping the coating over a chosen surface
area with the difference of weights before and after the coating is
removed providing the weight of the coating over an area.
[0004] The coil coating process generally involves multiple layers
of coating starting from a pretreatment followed by a primer and
top coating. It is important to continuously monitor the applied
coating accurately as any under-application of coating generally
results in poor product performance and the costs of repairing or
replacing under-applied coated coils are substantial. There are
currently no reliable tools to accurately measure the thickness of
these coatings in real-time directly on the metal coil itself
during the coating process. The primer and top coat layers are
usually pigmented and most optical tools are limited to measuring
transparent or mildly pigmented coatings and even that is limited
to offline measurements in most cases. The only alternate methods
for measuring the coating thickness in real-time involve indirect
measurements of the paint on the coating applicator rather than
direct measurements of the coated coil itself. At best, the
indirect measurements of the coating applicator are approximations
of the coatings that may eventually be transferred to the metal
coil. Moreover, although there are several optical measurement
tools and techniques that can measure thickness of transparent or
semi-transparent layers, there are no existing tools or
technologies that can directly measure the thickness of a heavily
pigmented layers (with a pigmentation level of 40% or more) on
metal coils of any variety for up to 75 microns.
[0005] Thus, there remains a need for methods and systems for
direct optical measurement of pigmented coatings on static or
moving metal coils in real-time.
SUMMARY OF THE INVENTION
[0006] The present invention relates to measuring and monitoring
accurate coating thickness of heavily pigmented coatings on metal
substrates such as aluminum and steel with pretreatment using the
reflectance spectra which is obtained using broad spectral range
optical system with array detector when the coating thickness is
between 1 and 75 microns. The measured thickness could be a single
layer of pigmented coating, multiple pigmented coatings or a
combination of transparent and pigmented coatings on metals. The
present invention relates to specifically measuring the primer and
top coat thickness in real time at production line speeds on one or
both sides of the coil simultaneously.
[0007] In one embodiment of the present invention, a method for
measuring the thickness of coatings on metal substrates may include
illuminating a sample comprising a substrate and a coating with
light waves of varying wavelengths from a light source. The method
may further include receiving the light waves reflected by the
sample at a light collector. The method may further include
diffracting the light waves into a plurality of component
wavelengths with a grating. The method may further include
detecting the light intensities of the plurality of component
wavelengths at a detector array. The method may further include
generating a reflectance spectral curve using the light intensities
for each of the plurality of component wavelengths. The method may
further include calculating the thickness of the coating from the
reflectance spectral curves of the component wavelengths.
[0008] In another embodiment of the present invention, a system for
measuring the thickness of coatings on metal substrates may include
a processor and a light source in communication with the processor,
the light source configured to illuminate a sample comprising a
substrate and a coating with light waves of varying wavelengths.
The system may further include a detection module in communication
with the processor. The detection module may include a light
collector configured to receive light waves reflected by the
sample, a grating configured to diffract the light waves into a
plurality of component wavelengths, and a detector array configured
to detect the light intensities of the plurality of component
wavelengths. The system may further include a memory in
communication with the processor, wherein the memory comprises
computer program code executable by the processor. The computer
program code may be configured to generate a reflectance spectral
curve using the detected light intensities for each of the
plurality of component wavelengths, calculate the thickness of the
coating from the reflectance spectral curves of the component
wavelengths, and display the calculated thickness of the coating in
real-time.
[0009] In yet another embodiment, the sample may be continuously
moving.
[0010] In yet another embodiment, the light waves of varying
wavelengths may be between about 1000 nm and about 2500 nm.
[0011] In yet another embodiment, the light source may be part of a
bifurcated fiber optic cable.
[0012] In yet another embodiment, the light collector may be part
of a bifurcated fiber optic cable.
[0013] In yet another embodiment, the grating may match the
spectral response over a specific wavelength range suitable for the
sample.
[0014] In yet another embodiment, the frequency of the reflectance
spectral curve may be directly proportional to the thickness of the
coating.
[0015] In yet another embodiment, calculating the thickness of the
coating may occur in real-time.
[0016] In yet another embodiment, a sensor may be configured to
detect changes in the distance between the sample and the light
source.
[0017] In yet another embodiment, illuminating the sample may
include varying the intensity of the light waves based on the
distance between the sample and the light source.
[0018] In yet another embodiment, a coating applicator in
communication with the processor may be configured to receive the
calculated thickness of the coating and adjust the amount of
coating applied to the substrate in real-time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] These and other objects, features, and characteristics will
become more apparent to those skilled in the art from a study of
the following Detailed Description in conjunction with the appended
claims and drawings, all of which form a part of this
specification. While the accompanying drawings include
illustrations of various embodiments, the drawings are not intended
to limit the claimed subject matter.
[0020] FIG. 1 is a diagram of a prior art coil coating line.
[0021] FIG. 2 is a block diagram of a system for measuring the
thickness of coatings on metal substrates according to an
embodiment of the present invention.
[0022] FIG. 3 is a diagram of a detection module according to an
embodiment of the present invention.
[0023] FIG. 4 is a flow chart diagram of a method for measuring the
thickness of coatings on metal substrates according to an
embodiment of the present invention.
[0024] FIG. 5 is a graph of the spectral response of a light source
according to an embodiment of the present invention.
DETAILED DESCRIPTION
[0025] The presently disclosed subject matter is presented with
sufficient details to provide an understanding of one or more
particular embodiments of broader inventive subject matters. The
descriptions expound upon and exemplify particular features of
those particular embodiments without limiting the inventive subject
matters to the explicitly described embodiments and features.
Considerations in view of these descriptions will likely give rise
to additional and similar embodiments and features without
departing from the scope of the presently disclosed subject
matter.
[0026] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood to one of
ordinary skill in the art to which the presently disclosed subject
matter pertains. Although any methods, devices, and materials
similar or equivalent to those described herein can be used in the
practice or testing of the presently disclosed subject matter,
representative methods, devices, and materials are now
described.
[0027] Following long-standing patent law convention, the terms
"a", "an", and "the" refer to "one or more" when used in the
subject specification, including the claims. Thus, for example
reference to "a light source" can include a plurality of such light
sources, and so forth.
[0028] Unless otherwise indicated, all numbers expressing
quantities of components, conditions, and so forth used in the
specification and claims are to be understood as being modified in
all instances by the term "about". Accordingly, unless indicated to
the contrary, the numerical parameters set forth in the instant
specification and attached claims are approximations that can vary
depending upon the desired properties sought to be obtained by the
presently disclosed subject matter.
[0029] As used herein, the term "about", when referring to a value
or to an amount of mass, weight, time, volume, concentration,
and/or percentage can encompass variations of, in some embodiments
+/-20%, in some embodiments, +/-10%, in some embodiments +/-5%, in
some embodiments +/-1%, in some embodiments +/-0.5%, and in some
embodiments, +/-0.1%, from the specified amount, as such variations
are appropriate in the disclosed products and methods.
[0030] Referring now to FIG. 1, a prior art coil coating line 1 is
shown. A typical coil coating line 1 may consist of an entrance
accumulator 11 that provides a reservoir of uncoiled metal
substrate received from uncoiler 10. The entrance accumulator 11
may be followed by pre-treatment from a cleaning and conversion
coating apparatus 12 followed by the application of primer coatings
from a prime coater 13 on both sides of the coil. The primer
coating is cured in the curing oven 14 before a top coat (or finish
coat) is applied by the top coater 15 on top of the primer on both
sides of the metal coil. The metal substrate with the coating may
then be finished in the finish oven 16 and recoiled by the recoiler
17. All aspects of the coil coating line 1, including the speed of
the coil substrate and the amount of coating applied, may typically
be controlled with a computer (not shown).
[0031] According to some embodiments of the present invention, the
systems and methods of the present invention may be in
communication with the computer controlling the coil coating line,
the computer configured to receive the calculated thickness of the
coating and adjust the amount of coating applied to the substrate
in real-time. Because the response time of the measurement of the
in-process measurement system in the present invention is in
milliseconds, there may be a realtime feedback on the thickness of
the applied coating. Due to the realtime feedback, the application
of the coating can be controlled by the coating machine so that the
coating is not only uniform across the width of the coil, but also
is not overapplied, resulting in significant amount of coating
savings when considering production on an industrial scale. On the
other hand, the present invention may also help eliminate
underapplication of coating which results in significant savings
for coil coating manufacturers in reducing scrap and avoiding
expensive quality claims.
[0032] Referring now to FIG. 2, a system for measuring the
thickness of coatings on metal substrates according to one
embodiment of the present invention is shown. The system may
include a processor 20 and a light source 21 in communication with
the processor 20, the light source 21 configured to illuminate a
sample comprising a substrate and a coating with light waves of
varying wavelengths. The system may include a detection module 23
in communication with the processor 20 comprising: a light
collector 22 configured to receive light waves reflected by the
sample, a grating configured to diffract the light waves into a
plurality of component wavelengths, and a detector array configured
to detect the light intensities of each of the plurality of
component wavelengths. The system may further include a memory 24
in communication with the processor 20, wherein the memory 24
comprises computer program code executable by the processor 20. The
computer program code may be configured to: generate a reflectance
spectral curve using the detected light intensities for each of the
plurality of component wavelengths, calculate the thickness of the
coating from the reflectance spectral curves of the component
wavelengths, and display the calculated thickness of the coating in
real-time.
[0033] The processor 20 may receive input signals from and generate
instruction signals for the coil coating applicator controller 26
to process sensor readings to measure or adjust thickness of
coatings in real-time. The processor 20 may also communicate this
data to a display 27, allowing operators to observe the data in
real-time. The processor 20 may include or may be in communication
with one or more computer-readable media, such as a memory 24. The
processor 20 may further execute computer-executable program
instructions stored in memory 24. The processor 20 may comprise a
microprocessor, a digital signal processor (DSP), an
application-specific integrated circuit (ASIC), one or more field
programmable gate arrays (FPGAs), or state machines. The processor
20 may further comprise a programmable electronic device such as a
PLC, a programmable interrupt controller (PIC), a programmable
logic device (PLD), a programmable read-only memory (PROM), an
electronically programmable read-only memory (EPROM or EEPROM), or
other similar device.
[0034] The memory 24 may comprise a computer-readable media that
may store instructions, which, when executed by the processor 20,
cause it to perform various steps, such as those described herein.
Embodiments of computer-readable media may comprise, but are not
limited to, and electronic, optical magnetic, or other storage or
transmission device capable of providing the processor 20 with
computer-readable instructions. Other examples of media comprise,
but are not limited to, a floppy disk, CD-ROM, magnetic disk,
memory chip, ROM, RAM, ASIC, configured processor, all optical
media, all magnetic tape or other magnetic media, or any other
medium from which a computer processor can read. Also, various
other devices may include computer-readable media, such as a
router, private or public network, or other transmission
device.
[0035] According to some embodiments, a bifurcated fiber optic
cable 25 may be used for transmitting the light from the light
source and also to detect the light coming back from the light
sample. The light source leg of the bifurcated fiber optic cable 25
may consist of 6 illuminating fibers and the second leg of the
bifurcated fiber optic cable 25 may consist of one detecting fiber.
In preferred embodiments, light waves may be provided by a tungsten
halogen broadband light source or other suitable broadband light
source with adequate energy response in the wavelength range of
operation and the spectral response shown in FIG. 5.
[0036] Referring now to FIG. 3, a detection module 30 according to
an embodiment of the present invention is shown. The detection
module 30 may be comprised of several optical components. The
detection leg of the fiber optic cable may be attached to an SMA
connector 31, followed by a fixed entrance slit 32 (which
determines the optical resolution of the detector configuration).
The light that passes through the fixed entrance slit 32 may be
illuminated on a collimating mirror 33 and reflect from the
collimating mirror 33 as a collimated beam towards the grating
34.
[0037] According to some embodiments of the present invention, the
grating 34 may match the spectral response over a specific
wavelength range suitable for the sample. The grating 34 may a
dispersive optical component which splits and diffracts light into
different wavelength components. The grating 34 may be carefully
chosen to match the sectral response over a specific wavelength
range that is suitable for different chemical compositions and
paint colors used for coil coating industry according to method
known in the art. The different light beams from the grating 34 may
then be directed to a focusing mirror 35 and the focusing mirror 35
may focus the first order spectra on the detector array 36. The
detector array 36 may have at least 256 elements collecting the
reflectance data at 256 discrete wavelengths.
[0038] Referring now to FIG. 4, a method for measuring the
thickness of coatings on metal substrates according to one
embodiment of the present invention is shown. The method may
include at step 40 illuminating a sample comprising a substrate and
a coating with light waves of varying wavelengths from a light
source. The method may further include at step 41 receiving the
light waves reflected by the sample at a light collector. The
method may further include at step 42 diffracting the light waves
into a plurality of component wavelengths with a grating. The
method may further include at step 43 detecting the light
intensities of the plurality of component wavelengths at a detector
array. The method may further include at step 44 generating a
reflectance spectral curve using detected light intensities for
each of the plurality of component wavelengths. The method may
further include at step 45 calculating the thickness of the coating
from the reflectance spectral curves of the component
wavelengths.
[0039] According to some embodiments of the present invention, the
sample may be continuously moving. In such embodiments, measuring
the coating thickness in real-time may require consideration of web
flutter in the sample metal coil. As the metal coil is coated at
high speeds, there may be a certain amount of web flutter (up and
down motion across the width of the coil). This poses a significant
challenge for most optical tools because traditional optical tools
use actual values of reflectance to calculate the thickness of the
coating and the up and down motion of the coil will have such a
significant impact on the actual reflectance value that it makes
the measurements highly unreliable in-process.
[0040] According to some embodiments of the present invention, the
method may further include at step 46 detecting changes in the
distance between the sample and the light source. When either the
sample moves too close to the fiber optic light collector or when
the sample goes too far from the fiber optic light collector, the
detected light intensities will be beyond an acceptable range. When
such light intensities are detected, the systems according to the
present invention can compensate for the change in distance as
described further herein. The system may be calibrated to predefine
acceptable ranges of light intensities.
[0041] According to some embodiments of the present invention,
illuminating the sample may include at step 47 varying the
intensity of the light waves based on the distance between the
sample and the light source. By controlling the intensity of the
light in real-time, the effects of web flutter can be mitigated. If
the sample moves closer to the sensor then the intensity of the
incident light may be reduced, and similarly, if the sample moves
farther away from the sensor, the intensity of the incident light
may be increased. After calculating the thickness of the coating,
if it is determined that the distance between the sample and the
light source has changed due to web flutter, the intensity of the
light may be changed before the next measurement is taken.
[0042] According to some embodiments of the present invention, the
light waves of varying wavelengths may be between about 1000 nm and
about 2500 nm. In preferred embodiments, light waves in this
wavelength range may be provided by a tungsten halogen broadband
light source or other suitable light source with adequate energy
response in the wavelength range of operation and the spectral
response shown in FIG. 5.
[0043] A portion of the light waves that are illuminated on the
coated sample reflect from the top of the coating and a portion of
the light waves passes through the coating and reflect from the
bottom of the top of the substrate. The reflectance values may be
collected on all the discrete wavelengths in a time span of
approximately 50 milliseconds or less. The two reflected light
waves may be mathematically superimposed to generate a resultant
reflectance spectral curve. The spectral curve will take the shape
of a periodic waveform. The frequency of the resulting periodic
wave may be directly proportional to the thickness of the measured
coating. The resultant spectral curve will have p- and s-polarized
components of reflectance that generally satisfy the following
equations:
R p = n 1 cos .theta. t - n 2 cos .theta. i n 1 cos .theta. t + n 2
cos .theta. i 2 = n 1 1 - ( n 1 n 2 sin .theta. i ) 2 - n 2 cos
.theta. i n 1 1 - ( n 1 n 2 sin .theta. i ) 2 + n 2 cos .theta. i 2
. R s = n 1 cos .theta. i - n 2 cos .theta. t n 1 cos .theta. i + n
2 cos .theta. t 2 = n 1 cos .theta. i - n 2 1 - ( n 1 n 2 sin
.theta. i ) 2 n 1 cos .theta. i + n 2 1 - ( n 1 n 2 sin .theta. i )
2 2 , ##EQU00001##
[0044] In the above equations, n.sub.1=complex refractive index of
the coating, n.sub.2=complex refractive index of the substrate,
.theta..sub.i=angel of incidence, .theta..sub.t=transmission angle,
R.sub.p=p-polarized reflectance component, and R.sub.s=s-polarized
reflectance component. The p and s polarized reflectance components
are a function of wavelength and have a reflectance value at each
wavelength.
[0045] According to some embodiments of the present invention, the
frequency of the reflectance spectral curve may be directly
proportional to the thickness of the coating.
[0046] According to some embodiments of the present invention,
calculating the thickness of the coating may occur in real-time.
One of ordinary skill in the art will appreciate that the term
"real-time" refers to the ability to perform measurements and
calculate thickness from said measurements with minimal delay--on
the order of 100 milliseconds or less.
Illustrative System 1
[0047] Since the primer and the top coat are applied sequentially
at two different stages on both sides of the coil, a complete
overall real-time measurement system may consist of the following
combination of individual inline systems: an in-process measurement
system measuring the front side of the coil where primer is
applied, an in-process measurement system for measuring back side
of the coil where the primer is applied, a third system for
measuring the total thickness of the primer and top coat on the
front side of the coil where the top coat is applied on top of
already applied primer, an in-process system for measuring the
total thickness of the primer and the finish coat on the back side
of the coil where the back coat is applied on top of already
applied primer.
[0048] The measurement systems on the front side of the primer and
the top coat may be linked and communicate with each other, and the
thickness of the top coat can be obtained by dynamically
subtracting total thickness of the front side of the coil and the
primer thickness of the front side of the coil.
[0049] The measurement systems on the back side of the primer and
the back side of the finish stage may be linked and communicate
with each other, and the thickness of the back coat can be obtained
by dynamically subtracting total thickness on the back side of the
coil and the primer thickness on the back side of the coil.
Illustrative System 2
[0050] The present invention performs equally well for measuring
wet coatings in-process with slight modification. Some
manufacturers may prefer measurement of wet coating compared to a
dry coating to get feedback on the amount of applied coating and
coating consistency earlier in the process before going through the
finish oven. The following components may be included in a
multi-stage wet measurement system: an in-process measurement
system measuring the wet coating before it goes into the overn on
front side of the coil where primer is applied, an in-process
system for measuring wet coating before it goes into the overn on
the back side of the coil where the primer is applied, an
in-process system for measuring the total thickness of the primer
and wet top coat on the front side of the coil where the top coat
is applied on top of already applied primer, an in-process system
for measuring the total thickness of the dry primer and the wet
finish coat on the back side of the coil where the back coat is
applied on top of already applied primer.
[0051] The dry thickness of the primer may be calculated from the
wet thickness of the primer on both sides of the coil based on the
percentage of solids by volume in the primer provided by the primer
manufacturer.
[0052] The measurement systems on the front side of the primer and
the top coat may be linked and communicate with each other, and the
thickness of the top coat can be obtained by dynamically
subtracting the calculated dry primer from the total thickness of
the wet top coat and dry primer. Similarly, dry top coat thickness
may be calculated from the wet thickness of the top coat based on
the percentage of solids by volume in the top coat provided by the
top coat manufacturer.
[0053] The measurement systems on the back side of the primer and
the back coat may be linked and communicate with each other, and
the thickness of the back coat can be obtained by dynamically
subtracting the calculated dry primer from the total thickness of
the wet back coat and dry primer. Similarly, dry back coat
thickness may be calculated from the wet thickness of the back coat
based on the percentage of solids by volume in the back coat
provided by the back coat manufacturer.
[0054] Those skilled in the art will recognize improvements and
modifications to the embodiments of the present disclosure. All
such improvements and modifications are considered within the scope
of the concepts disclosed herein and the claims that follow.
* * * * *